I agree with Cindy. David, I have done what you suggest a few times. About half the time I have been pleased with the results and half not so much. :-)
If you think about it, in nature random sowing is what often happens.
One other thing to be aware of though. Height of plants. For example, if you planted 2 types - 1 grows to 3 plus feet and the other grows to 6 inches. The latter will fail cause the other will shade the smaller one.
Finally - obviously do not mix full sun with shade only. :-)
Good luck.
